The invention relates to a method of controlling rock drilling performed by a rock drill provided with a pressure-driven hammer and a rotation motor, the rock drilling in the method being controlled by different control parameters, one of which is the speed of rotation of the drill rod.
In rock drilling, the drilling is typically controlled by different parameters, the most general of which are the feed pressure, rotation pressure, and the impact pressure of the hammer. These values are typically transformed into electric signals, by which a computer can control the drilling in accordance with the desired limits or algorithms. In the drilling, the speed of rotation of the drill rod is also defined in different ways. In a manual solution, it is determined by rough estimation. The solution used in computer-controlled xe2x80x98data equipmentxe2x80x99 is one in which the value of the control signal supplied to the electrically-driven valve is indicated as percentages of the maximum control range. It is also possible to use an electric sensor located at the rotation motor or in its transmission box, the sensor making it possible to measure the speed of rotation of the drill rod.
One of the drawbacks of these solutions is that the visual estimation of the speed of rotation is difficult and inaccurate. On the other hand, the speed of rotation expressed in percentages is difficult to understand. Further, a separate sensor measuring the speed of rotation in a rock drill is susceptible to damage and so it is not necessarily reliable.
Another problem here is that these values of the speed of rotation are in fact not utilized in any way in controlling the drilling. Therefore, the speed of rotation is set approximately to a value estimated to be suitable, and the actual drilling control is conducted by adjusting the other parameters.
The object of the present invention is to provide a method of controlling rock drilling, in which the speed of rotation of the drill rod is measured reliably and by which it can be used to control the actual rock drilling in a suitable manner. The method of the invention is characterized in that for the control, the speed of rotation of the drill rod is defined on the basis of the value of the control signal used to control the control valve that adjusts the flow of the pressure fluid supplied to the rotation motor, and that the value of the control signal indicating the speed of rotation is used as a control parameter.
The essential idea of the invention is that the control voltage or control pressure of the control valve of the rotation motor is measured, and that the voltage and pressure are converted to correspond to the speed of rotation by suitable scaling. Since the volume flow produced by the control voltage or pressure through the rotation motor can be expressed as a linear straight line, the converted control voltage and pressure correspondingly yield a linear speed of rotation. The essential idea of a preferred embodiment of the invention is that the parameter, such as the control pressure, expressing the speed of rotation is used in addition to the other parameters to control the rock drilling.
The advantage of the invention is that when the control pressure or voltage of the control valve of the rotation motor is used to indicate the speed of rotation, a reliable speed-of-rotation indicator, which is not easily damaged, is obtained. The speed of rotation can thus be controlled both manually and in other ways with the desired accuracy. Further, when in addition to the other control parameters the control element, or pressure signal or electric signal, of the control valve of the rotation motor is used to control the rock drilling, any changes in the conditions, for example in the fissure automation, can be taken into account, and the speed of rotation can be adjusted to be optimal in respect of the impact. Further, if the feed pressure control is based on the rotation pressure, i.e. moment adjustment is used, the parameter indicating the speed of rotation can be used to control the correct operational value.